Automatic boiler control system



Jan. 1, 1946. H. ZIEBOLZ ET AL 2,392,300

' AUTOMATIC BOILER CONTROL SYSTEM Filed June 12, 1942 COUP LINGREGULATOR MASTER RmuLAroR COUPLING COOLER Patented Jan. 1, 1946 UNITEDST TE PATENT c rr es 2,392,300 aurom'rrc nomna oorrmor. srsrnu I HerbertZiebola, James D. McGracken, and Daniel '1. Gundersen, Chicago, 111.,assignors to Askania Regulator Company, Chicago, Ill., a corporation ofIllinois Application June 12, 1942, SerialNo. 440,150 (or, 60-44) xpiston I9 is connected to operate a second cam 3 Claims.

This invention relates to an automatic boiler control system or the typeemploying a master regulator responsive to the boiler load or steampressure in the header and a hydraulic coupling controlled thereby tosupply the combustion supporting air to support combustion of the fuelin the boiler furnace. One of the main objects of the invention is toprovide automatic control means for a hydraulic coupling employingservomotors having cross connected cylinders for controlling t'he valvesin the lines or pipes-connected to the coupling, the idea being toprevent the valves from being operated simultaneously and to avoid theusual dead spot in such a control. Furthermore, the idea is to provide asystem of this type in which the control valves will close and remainclosed so that the coupling can be operated by an ordinary hand controlin case of oil failure. Another object is to provide control means forthe coup which is not subjected to undue friction and increasing thepossibility of a dead spot in the control valves. Still another objectis to provide improved control means for such hydraulic couplingsadapting them for general use. A further important object of theinvention is to so interconnect the valve control means for thehydraulic coupling that the valves will be operated in a specific mannerand also to provide a bubbling device as a level indicator of hydraulicfluid which acts as a generator oi control impulses for the operation ofthe valve control means.-

Other aims and advantages of the invention will appear in thespecification, when considered in connection with the accompanyingdrawing, in which:

23 which acts on a second Jet pipe relay 24 through a. spring 25 inopposition to a diaphragm 26 which. in turn, is subjected to a pressureproportional to the level of oil in the oil sump 21 or a hydrauliccoupling later to be described.

The diaphragm 26 is shown as being arranged in a casing 28 to which isconnected a pipe 29 having its opposite end '30 extending to a pointnear the bottom of the sump 21 and submerged in the oil therein. To thispipe is connected an air conduit 3| through which is introduced air at asuitable bubbling rate by means .of a throttle 4 valve 32a and apressure reducing valve 32. The

\ regulator and is shown as controlling two servo- The figure is adiagrammatic illustration of boiler furnace it. The boiler H is shown as'having an ordinary steam main or header H to which is connected. abellows-type pressure air will bubble out of pipe end 33 and maintainthe pressure in pipe 23 proportional to the submerged depth or pipe end30, so that when the oil level in the sump remains constant, the airpressure acting on the diaphragm 26 will likewise remain constant. Ifthe oil level falls in the sump, the air will bubble up through it morereadily from the end or opening 30 and thereby reduce the pressure ofthe air in the line 23 and in the casing 28. The valve 32a is adjustedto bleed air into line 29 at a rate Just suflicient to keep activebubbling at the pipe end 30.

The jet p pe 24 forms a part of the coupling motors or valve controlmeans in the form of cylinders 33 and 34 carrying spring urged istons 35and 36 respectively. The fluid pipes 31 and 33 leading from thejet piperelay 24 are shown as being cross connected to the cylinders 33' and 34,the pipe 31 being connected to the outer end of cylinder 34 and also tothe inner end of cylinder 33 by means of branches 33 and respectively;while thepipe 38 is connected to the outer end of cylinder 33 and to theinner end of cylin-' der 34 by means 01' branches 41 and 42respectively. Piston rods 43 and 44 extend through the outer ends of thecylinders 33 and 34 respectively, each cylinder having an unpackedbearing seal or bailie around the piston rod. The oil which leaks pastthe bearing seals, is drained through drain pipes 45 and .46 at theouter ends of =the cylinders. The piston rods 43 and 44 are operateddiaphragm l3 acting on a pivoted lever 14 carrying the usual weight I!which .is a function 'of the boiler pressure. The pivoted lever 14 actson an ordinary jet pipe regulator or relay It in opposition to a spring11, the compression of which is controlled orrggulated by the cam 13connected to be actuated by a piston 13 in a 1 cylinder 23, the lattercommunicating with the Jet pipe relay w-throuahpipea' 2| and 22,. The

connected through pivoted levers 41 and 43, re-' I spectively, tooperate control valves 43- and 7 coupling 33 through the pipe '52 and acooler 53 is shown as being connected between the supply and drain pipes32 and II.

The arrangement of the control means for the valves 49 and 50 is suchthat only one valve is operated at any time and the other has to waituntil said one valve is closed to be actuated. For normal variations inthe condition under 'regulation', the pistons 35 and 35 will actuallywait upon each other to return by spring action to their normalpositions. For example. if piston 35 is displaced from normaland piston35 is required to move, the piston 36 will have to wait upon piston 35to return to its normal position before it can move. This surprisingoperation is due to the orifice action of the two orifices in the jetpipe relay 24. When one piston is moving, oil flows into one orifice andout the other through pipes 31 and 33. There is a positive drop in thepressure in the line where oil fiows in and a rise or negative drop inpressure in the line through which the oil flows out. If the pistons areheld fixed and the jet of the relay 24- is moved a certain distance tothe left, the pressure in the branches 39 and 40 will increase; whilethe pressure in branches 4| and 42 will be somewhat less, say about 55#and 45#, respectively. If the jet is displaced in the opposite directionor to the right of the center, the pressure in the branches 4| andv 42will increase and the pressure will decrease in branches 39 and 40. If,with the jet pipe displaced to the left and pressures of, say 55# and45# respectively present in the branches 39-40 and 4l-42 respectively,the pistons are released, the piston 35 will move and the piston 35 willremain stationary,

31 and out of pipe 38. Then the pressure in the pipe 31, due to' the oilflow, will drop to, say 52# and the pressure in pipe 38 will riseslightly to, say 48#. Now, if the Jet pipe of relay 24 is' displaced thesame distance to the right of center, piston 33 will reverse itsmovement and hasten back to its normal or valve closing position. Oilwill then flow rapidly through the branch 4| and pipe 33 and keep thepressure in the branches 38 and 40 actually less than 50# and thepressure in 4| and 42 will be more than 50#, thus preventing the piston35 from moving. As soon as the piston 35 stops moving, the pressuresimmediately change to about, say 55# and 45# in the conduits 38 and 31respectively and as soon as movement begins, it will almost immediatelychange to about 52# and 48# respectively, due to the flow of oil causedby the positive and negative drops across the'orifices in the Jet piperelay 24. In this way, one valve waits to start until the other hasreturned to normal waiting position,

It will be understood that the hydraulic coupling 53 is driven by anordinary motor M and is connected to operate the fan 53 at variablespeeds depending upon the air requirements for the boiler furnace andcontrolled by the amount asoasoo and the drawing. The bubbling device 30measures the oil level in the sump 21 and this level determines the oillevel in the coupling 53. In most instances, the level in the couplingis inversely proportional to that in the sump. The bubbling device 30has a further function in that it acts as a generator of controlimpulses for the.

diaphragm 25 which acts on the jet pipe relay 24 to actuate'thevalves 49and 50 through the servo-motors or valve control means 35 and 35. Thus,the pressure maintained in the line is proportional to the depth of thesubmerged end 30 and is a function of the oil level in the coupling.

011 would then be flowing into pipe I The system according to theinvention has many advantages and particularly the diiferen tialoperation of the piston motors 35 and3 eliminates the necessity of apacking and with the drain lines and 45 the motors are practicallyfriction free. The springs in the motors are just sufficient to keep thevalves closed or drag and results in a practically friction free motor.

The cross connections 33 and 4| result in the operation of the pistonsor servo-motors 35 and 35 in such a way that they will actually waitupon each other to return to normal position; that is if one isreturning to normal-l position, the other will not move until the firstone reaches normal.

' In other words, if piston 35 is displaced from normal and piston 38 isrequired to move, piston 35 will wait for piston 35 to return to normal1 before starting to move. This, as has been exof oil fed to thecoupling. The fan 55 delivers air to the boiler furnace through aconduit 51.

In this instance, fluid fuel is delivered to the furnace through aconduit 53 and its supply is controlled by an ordinary Jet piperegulator 53 connected to be operated by differential furnace pressurethrough the usual diaphragm 50 plained. is due to the orifice action ofthe two orifices in the relay 24, since when a piston 35 or 35 ismoving, oil is flowing in its respective orifice and out of the otherorifice. There is a positive drop'in the pressure in the line when theoil flows in and a negative drop or rise in pressure in the line whenthe oil flows out of the orifice. In this way, one valve waits to startuntil the other has returned to normal waiting position.

ventlon utilizes thefull sensitivit of the control and reduces the deador insensitive spot in a control -to a minimum to thereby improve thestability of the control and eliminate hunting.

It is of course obvious that all features shown and described need notbe used conjointly. Also, the invention is not limited to the exactembodiment shown and it is not indispensable that all the features ofthe invention be used conjointly, since they may be employedadvantageously in various combinations and sub-combinations.

We claim as our invention:

1. In an-automatic control system of the class described including ahydraulic coupling and embodying a pair of valve controlled conduits forthe coupling fluid and a regulator tor the coupling including a jet piperelay responsive to. a controlled condition aflected by the coupling, adevice for operating the valves in said conduits comprising a pair ofdouble-acting servo-motors tive outlet pipes of the jet pipe relay, andsaid cross-connections preventing simultaneous operation of the valves.

2. An automatic control system, as set forth in claim 1, in which thesystem is provided with an oil sump to; the hydraulic fluid and an airbubbling device is associated with the oil sump and connected to createcontrol impulses-acting on the jet pipe relay in response to changes inlevel of the coupling fluid in the sump. 4

3. An automatic control system, as set forth in claim 1, wherein theservo-motors havepiston rods projecting through oil baiiles near one end01' each cylinder to prevent friction and wherein an oil drain isconnected-to each cylinder beyond said haiiies. v

HERBERT ZIEBOLZ. JAMES D. McCRACKEN DANIEL T. GUNDERSF

